1. Technical Field
The present invention relates to Voice over Internet Protocol (VoIP) telephony, and more particularly to properly routing and enhancing emergency-services (911) VoIP calls.
2. Description of Related Art
In recent history, specifically in the latter half of the 20th century, a standardized system emerged for people to use when the need arose to place a telephone call to request emergency services. In particular, it has become almost universal in the United States, that, when a person places such an emergency-services call, they do so by dialing 911. This typically results in the caller being connected with a call-answering center typically known as a public safety answering point (PSAP). An operator at the PSAP may then connect the caller with a first responder suited to the caller's particular emergency, to the extent that it can be determined during the call.
It is too often the case, however, that emergency-services (911) calls are disconnected at critical times. Furthermore, it is also too frequent that a caller is unable to adequately convey their location to a PSAP operator, perhaps due to any number of reasons such as age, language barriers, a need to keep quiet in dangerous circumstances, health reasons related or unrelated to the emergency giving rise to the call, and so on. In response to these phenomena, a concept known as “Enhanced 911” (E911 or E-911) was conceived and implemented. E-911 calls are enhanced in the sense that certain signaling elements and databases are leveraged in order to automatically present both a callback number and the caller's location to the PSAP. This way, the PSAP operator can reach the caller in the event of an unintentional or necessary disconnection of the call, and the caller's location is readily available to the operator, obviating the need for the caller to successfully convey that location as a prerequisite to receiving aid.
Standing on the shoulders of the recent and continuing surge in popularity of the Internet, certain companies have begun offering telephony communications over the Internet. These communications are commonly known as Voice over Internet Protocol (VoIP) communications. The companies that offer this service to subscribers may be known as VoIP service providers (VSPs). Note that a particular person's VSP is not necessarily the same as that person's Internet Service Provider (ISP), which provides general access to the Internet. For example, a user may have general Internet connectivity via a cable modem provided by their ISP. This cable modem may have a port generally or specifically suitable for connecting a telephone adapted for VoIP communications (a “VoIP telephone”). When the user places a call using the VoIP telephone, the telephone may communicate via the cable modem, the ISP, and the Internet with a server maintained by a VSP; the call may then be set up and perhaps conducted via that server.
The E-911 system described above works well in the context of conventional telephony communication conducted using conventional telephones, telephone lines, and circuit-switched communication. However, VoIP telephones are flexible in that they may be disconnected from the above-described cable modem, connected to the Internet anywhere else in the world, and then used in the manner described above. In this context, calls from that VoIP telephone will still emanate from the telephone number associated on a permanent basis with the VoIP telephone. That telephone number may then be associated through the user's account with the user's home address. Thus, an emergency-services call placed by the VoIP telephone from a location away from home (and perhaps via a different ISP altogether) could mistakenly be assumed by a PSAP to be emanating from the user's home address. This could cause a delay in providing aid or a failure to provide aid, with tragic or at least undesirable consequences.